Loop
freedom
of
the
(untimed)
AODV
routing
protocol

The Ad hoc On-demand Distance Vector (AODV) routing protocol allows
the nodes in a Mobile Ad hoc Network (MANET) or a Wireless Mesh
Network (WMN) to know where to forward data packets. Such a protocol
is ‘loop free’ if it never leads to routing decisions that forward
packets in circles.

This development mechanises an existing pen-and-paper proof of loop
freedom of AODV. The protocol is modelled in the Algebra of
Wireless Networks (AWN), which is the subject of an earlier paper
and AFP mechanization. The proof relies on a novel compositional
approach for lifting invariants to networks of nodes.

We exploit the mechanization to analyse several variants of AODV and
show that Isabelle/HOL can re-establish most proof obligations
automatically and identify exactly the steps that are no longer valid.